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  • In 1963, a 21-year-old physicist named Stephen Hawking

  • was diagnosed with a rare neuromuscular disorder

  • called amyotrophic lateral sclerosis, or ALS.

  • Gradually, he lost the ability to walk,

  • use his hands,

  • move his face,

  • and even swallow.

  • But throughout it all, he retained his incredible intellect,

  • and in the more than 50 years that followed,

  • Hawking became one of history's most accomplished and famous physicists.

  • However, his condition went uncured

  • and he passed away in 2018 at the age of 76.

  • Decades after his diagnosis,

  • ALS still ranks as one of the most complex,

  • mysterious,

  • and devastating diseases to affect humankind.

  • Also called motor neuron disease and Lou Gehrig's Disease,

  • ALS affects about two out of every 100,000 people worldwide.

  • When a person has ALS,

  • their motor neurons,

  • the cells responsible for all voluntary muscle control in the body,

  • lose function and die.

  • No one knows exactly why or how these cells die

  • and that's part of what makes ALS so hard to treat.

  • In about 90% of cases,

  • the disease arises suddenly, with no apparent cause.

  • The remaining 10% of cases are hereditary,

  • where a mother or father with ALS passes on a mutated gene to their child.

  • The symptoms typically first appear after age 40.

  • But in some rare cases, like Hawking's, ALS starts earlier in life.

  • Hawking's case was also a medical marvel because of how long he lived with ALS.

  • After diagnosis, most people with the disease live between 2 to 5 years

  • before ALS leads to respiratory problems that usually cause death.

  • What wasn't unusual in Hawking's case was that his ability to learn,

  • think,

  • and perceive with his senses remained intact.

  • Most people with ALS do not experience impaired cognition.

  • With so much at stake for the 120,000 people

  • who are diagnosed with ALS annually,

  • curing the disease has become one of our most important scientific

  • and medical challenges.

  • Despite the many unknowns,

  • we do have some insight into how ALS impacts the neuromuscular system.

  • ALS affects two types of nerve cells called the upper and lower motor neurons.

  • In a healthy body, the upper motor neurons,

  • which sit in the brain's cortex,

  • transmit messages from the brain to the lower motor neurons,

  • situated in the spinal cord.

  • Those neurons then transmit the message into muscle fibers,

  • which contract or relax in response,

  • resulting in motion.

  • Every voluntary move we make occurs

  • because of messages transmitted along this pathway.

  • But when motor neurons degenerate in ALS,

  • their ability to transfer messages is disrupted,

  • and that vital signaling system is thrown into chaos.

  • Without their regular cues, the muscles waste away.

  • Precisely what makes the motor neurons degenerate

  • is the prevailing mystery of ALS.

  • In hereditary cases, parents pass genetic mutations on to their children.

  • Even then, ALS involves multiple genes

  • with multiple possible impacts on motor neurons,

  • making the precise triggers hard to pinpoint.

  • When ALS arises sporadically, the list of possible causes grows:

  • toxins,

  • viruses,

  • lifestyle,

  • or other environmental factors may all play roles.

  • And because there are so many elements involved,

  • there's currently no single test that can determine whether someone has ALS.

  • Nevertheless, our hypotheses on the causes are developing.

  • One prevailing idea is that certain proteins inside the motor neurons

  • aren't folding correctly,

  • and are instead forming clumps.

  • The misfolded proteins and clumps may spread from cell to cell.

  • This could be clogging up normal cellular processes,

  • like energy and protein production, which keep cells alive.

  • We've also learned that along with motor neurons and muscle fibers,

  • ALS could involve other cell types.

  • ALS patients typically have inflammation in their brains and spinal cords.

  • Defective immune cells may also play a role in killing motor neurons.

  • And ALS seems to change the behavior of specific cells

  • that provide support for neurons.

  • These factors highlight the disease's complexity,

  • but they may also give us a fuller understanding of how it works,

  • opening up new avenues for treatment.

  • And while that may be gradual, we're making progress all the time.

  • We're currently developing new drugs,

  • new stem cell therapies to repair damaged cells,

  • and new gene therapies to slow the advancement of the disease.

  • With our growing arsenal of knowledge,

  • we look forward to discoveries that can change the future

  • for people living with ALS.

In 1963, a 21-year-old physicist named Stephen Hawking

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B2 US TED-Ed motor hawking disease degenerate hereditary

Why is it so hard to cure ALS? - Fernando G. Vieira

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    IS LIU posted on 2018/07/25
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